During the start of the Otah Gunga mission, walk into the room where Jar Jar is located. Start killing the guards. After you kill two guards, Jar Jar will repeat this statement, "Yousa start big fight. Yousa very bad!". He will start running to the
passageway to the left, but will not go anywhere. He will just be running in place. After all the guards are dead, Qui-Gon will say "Look out! Take cover!", after which a thermal detonator will kill Jar Jar.